cells and tissues 2 Flashcards
what are the layers of the basement membrane?
lamina lucida (top) lamina densa (bottom)
what is laminin?
protein of the basal lamina
explain the cause of Marfin’s syndrome
connective tissue disorder
elastin normally polymerises into fibrils and fibrillin coats it which limits how far it can stretch
in marfan’s, the fibrillin is misfolded so allows body parts to stretch abnormally - elastin cant recoil
what type of collagen is the basement membrane?
collagen type 4
name a disease caused by the mutation of laminin
junctional epidermolysis bullosa
explain the cause of junctional epidermolysis bullosa and how it presents
laminin is mutated
skin v fragile
blisters form in the lamina lucida
what are the types of epithelial junctions?
tight gap adherens hemidesmosomes desmosomes
what do tight junctions do?
prevent passage of molecules across the epithelium
what do adherens do?
tether adjacent cells together
what do desmosomes do?
resist mechanical stress
what do gap junctions do?
allow small passage of molecules through
what do hemidesmosomes do?
anchor epithelium to basal lamina
where are lots of desmosomes found?
in the heart
what do mutations of demosomes generally cause?
diseases of the skin and heart (impaired cardiac function)
what causes pemphigus vulgaris?
immune system attacks desmosomal proteins using autoantibodies causing epidermal blisters
what causes Staph. scalded skin syndrome?
when bacterial proteins are aimed at the desmosomal cadherins causing epidermal blisters
what causes Naxos disease and how is it presented?
genetic disease - mutation of desmoplakin
causes skin blisters, cardiomyopathy and wooly/curly hair
what is the function of non-motile cilia?
sensory antennae on all cells
what is the function of motile cilia?
to move things along
name some diseases of the cilia?
Bardet-Biedl syndrome
Polycystic kidney disease - abnormal primary cilia function
Ectopic pregnancy - lack of cilia in the fallopian tube
name the structures needed in cell movement and what they look like
pseudopodia - cytoplasmic projections
lamelliopodia - ruffles (cell migration)
filopodia - spikes (sense environment)
what does Escherichia coli target?
intestinal microvilli and junction
what does infection of Escherichia coli cause?
malabsorption
osmotic diarrhoea
what is the reticular lamina?
where the basement membrane attaches to the ECM protein
what is laminin?
protein of the basal lamina
what is connecitve tissue?
tissue that lies between 2 other tissues
what are the types of connective tissue?
loose dense bone and cartilag adipose blood
what are the cells that make connective tissue?
fibroblast adipocyte chondroblasts osteoblasts haemopoietic cells
what are the functions of ECM?
determines the function of the tissue has a role in; o Cell migration o Shape of the cell o Cell proliferation o Survival o Tissue development
what are the main macromolecules of the ECM?
GAGs and fibrous proteins
what are the main fibrous proteins in the ECM?
collagen
elastin
fibronectin
where are proteoglycans assembled?
ER and golgi
how do proteoglycans get to the ECM?
secretory vesicles
how do GAGs and proteoglycans resist compressive forces?
by binding water and forming hydrated gels
what is the advantage of hydrated gels?
resist compressive forces
permit rapid diffusion of nutrients, hormones and metabolites through them
give examples of sulfated GAGs
o Chondroitin sulfate
o Heparin sulfate
o Dermatan sulfate
what is hyaluronic acid used in?
wound healing
cell migration
growth
joints
what are proteoglycans?
protein core with GAGs attached
give examples of proteoglycans?
biglycan
aggrecan
syndecan
how does collagen form fibrils?
collagen filaments polymerise to form fibrils
what is Ehlers Danlos syndrome?
small collagen fibres which don’t come together so the skin can be pulled away – not held to the skin tightly. If it’s pulled too hard it would shear and tear.
what can fibronectin bind to?
cells via integrins
ECM via collagen
what are the roles of fibronectin?
cell attachment
matrix organisation
cell migration
development and wound healing
what does the basement membrane separate?
epithelium and underlying connective tissue
what is the basement membrane made of?
collagen type 4, laminin, heparan sulfate proteoglycan and entactin
what are the roles of the basement membrane?
support
anchoring
filter
signalling
what happens to the basement membrane in cancer?
basement membrane breaks down so the cancer can metastasise
what do the toxins of Escherichia coli cause?
o Destroy: Intestinal microvilli Intestinal junctions o Inhibit: Water reabsorption
